Physician anesthesiologist at Stanford at Associated Anesthesiologists Medical Group
Richard Novak, MD is a Stanford physician board certified in anesthesiology and internal medicine.Dr. Novak is an Adjunct Clinical Professor in the Department of Anesthesiology, Perioperative and Pain Medicine at Stanford University, the Medical Director at Waverley Surgery Center in Palo Alto, California, and a member of the Associated Anesthesiologists Medical Group in Palo Alto, California.

Imagine this scenario: You’ve just finished anesthetizing a patient in a hospital setting, and the patient now requires transport from the operating room (OR) to the post-anesthesia care unit (PACU). During surgery your patient monitors included: a pulse oximeter, an ECG, a blood pressure cuff, a temperature monitor, and a monitor of the oxygen, carbon dioxide, and anesthetic concentration of every breath inhaled and exhaled. During the transport to the PACU, a trip which can be as short as 1 minute or as long as 5 minutes, there are no specific standards regarding monitoring. It’s common for zero monitoring equipment to be attached to the patient. It’s also not uncommon for the patient to be breathing room air during transport. When you arrive at the PACU, a nurse reattaches your patient to the vital sign monitors, and discovers that the patient’s oxygen saturation has dropped from 100% in the OR to a severely low value of 80% in the PACU. 

Patients can have inadequate breathing on arrival at the PACU for multiple reasons, including oversedation from narcotics, oversedation from propofol or general anesthetic gases, residual paralysis from muscle paralysis drugs, upper airway obstruction, laryngospasm, obesity, sleep apnea, or pulmonary disease. An anesthesiologist can easily make a diagnosis of inadequate breathing if a patient is connected to a pulse oximeter. Should we routinely monitor a patient’s oxygen saturation level during transport to the PACU?  Let’s examine current standards and policies regarding anesthesia patient transport and review the published incidence of inadequate oxygenation following OR to PACU transport.

The American Society of Anesthesiologists (ASA) Standards for Post-Anesthesia Care state: 


This sounds like a reasonable standard, but it’s non-specific and leaves the decision regarding oxygen therapy and monitoring up to the individual member of the anesthesia care team’s judgment.

One the Harvard hospitals, Beth Israel Deaconess Medical Center, published the following policy regarding anesthesia transport:

Post Anesthesia Transport Monitoring 

After an anesthetic, the patient is usually transferred to the PACU or an ICU. This guideline sets out to clarify the type of patients who will need monitoring during transportation, and the nature of monitoring required. 

Monitoring during transport is mandatory for the following patients 

·  Any patient designated as needing ICU care, irrespective of whether the patient actually goes to the PACU or an ICU. 

·  Patients who are receiving vasopressors, vasodilators, or inotropes. 

·  Any patient who has a pulmonary artery catheter in situ.

·  All intubated patients. 

·  Any patient who has had an unstable course during the anesthetic. 

·  Any patient who needs to be transported for longer than 5 minutes to the recovery area.

The above list is not exhaustive and monitoring for transportation may be instituted for any patient at the discretion of the anesthesiologist. 

This is a reasonable policy, but what if anesthesia patient transport to the PACU lasts 4 minutes and 59 seconds (i.e. a long transport, but less than 5 minutes to the recovery area)?

The most common complications for in-hospital transported patients are respiratory, meaning that a patient has inadequate breathing and/or inadequate oxygen therapy during transport. The following five studies document that unmonitored patients frequently have low oxygen levels following transport to the recovery room.

In the 2012 study Does the transportation of patients from the operating room to the post-anesthetic care unit require supplemental oxygen? the authors prospectively looked at 50 patients transported from the OR to the PACU. They measured the oxygen saturation when each patient left the OR and when the patient arrived in the PACU. Moderate hypoxemia (oxygen saturation 86% to 90%) and severe hypoxemia (oxygen saturation less than 85%) occurred in 8% and 4% of patients, respectively. Seventy-five percent of the patients with moderate or severe hypoxemia were obese, and 42% were smokers. 

In the 2012 prospective study Hypoxemia after general anesthesia

959 patients underwent elective surgery under general anesthesia in a university hospital. All were transported to the PACU on room air without oxygen supplementation. The oxygen saturation level was measured at the end of the transfer to the PACU. Seventeen percent of patients had a pulse oximetry reading < 90%, and 6.6% had a pulse oximetry reading < 85%. The authors concluded that “transportation of patients breathing room air from the OR to the PACU directly after GA without use of PO or supplemental oxygen seems to be questionable in terms of patient safety.”

In the 2015 study, Impact of medical training clinical experience on the assessment of oxygenation and hypoxemia after general anesthesia: an observational study, anesthetists, nurses, and medical students estimated the oxygen saturation level in their patients at the end of transfer to the PACU, after the patients had been breathing room air during the transfer following surgery under general anesthesia. The estimated oxygen saturation level was compared to the actual oxygen saturation level measured by pulse oximetry. Low oxygen saturation (oxygen saturation < 90 %) occurred in 154 out of 1,138 patients (13.5 %). Anesthetists, nurses, and medical students accurately identified only 25, 23, and 21 of the 154 patients as being hypoxemic, respectively. The authors concluded that “considering the uncertainty about deleterious effects of transient, short-lasting hypoxemia, routine use of pulse oximetry is advocated for patient transfer to the PACU.”

In the 2016 study Predictors of desaturation during patient transport to the postoperative anesthesia care unit: an observational study13% of 505 patients had hypoxemia during transfer to the PACU. The three risk factors for low oxygen saturation were a Richmond agitation-sedation (RASS) score lower than -2, an oxygen saturation <96% before exiting the operating room, and a body mass index >30. Seventy-two percent of the patients were transferred without oxygen, and most of the hypoxemia appeared in these patients. The authors concluded that the development of hypoxemia during transfer from the OR to the PACU was greater in patients who were more sedated, obese, or had lower oxygen saturations when they left the OR. The authors also concluded that “supplemental oxygen should be considered in higher risk patients.”

In the 2020 study Complications associated with the anesthesia transport of pediatric patientsthe authors looked at a database of 2971 events pediatric adverse events, and 5% (148 events) were related to patient transport. The adverse events were primarily respiratory. Nearly 40% of the reported adverse events occurred in infants of an age less than or equal to 6 months. Seventy-five percent of the adverse respiratory events occurred postoperatively during transport from the OR to the PACU or the OR to the intensive care unit (ICU).

The distance from the OR to the PACU in the hospital I work at can be as much as 120 yards, and require anesthesia patient transport times of up to 5 minutes. The hospital supplies oxygen tanks on every gurney used to transport surgical patients from the OR to the PACU. The anesthesiologist administers nasal or mask oxygen to patients during transport.

Regarding respiratory monitoring during transport, a non-electronic monitor formerly utilized by anesthesiologists during patient transport was to pull a patient’s jaw toward the ceiling, with the palm of our hand of spanning across the patient’s mouth. In this manner we could feel each exhaled breath, documenting that the patient was breathing and ventilating themselves.

Since the arrival of COVID and the high risk of the spread of infection, anesthesiologists are wearing gloves whenever they are managing airways, and sensing a patient’s breathing through the thickness of the glove is ineffective. We need pulse oximetry monitoring.

to document adequate breathing and oxygenation. 

Every hospital owns portable vital sign monitors that look something like this:

portable vital sign monitor

These devices show real-time numeric values for the oxygen saturation, heart rate, ECG rhythm, and blood pressure, the same vital signs that are followed in the operating room. The acquisition cost for this monitor is currently $1300 per unit. If a hospital has 12 operating rooms, the total cost of 12 X $1300 = $15,600 is a reasonable investment to avoid patient complications of unstable vital signs during transport. 

What about a less expensive alternative? What about the inexpensive battery-powered pulse oximeters that clip over a fingertip are readily available at drug stores or on the internet. This product

$22.80 fingertip battery-powered pulse oximeter

is available on Amazon for $22.80, and has been reviewed by over 200,000 individuals to date. I bought one for my home and use it whenever a family member has respiratory viral symptoms. If a hospital stocked inexpensive oximeters like this one, doctors and nurses could diagnose low oxygen saturation in their patient(s) within seconds. Would these small portable devices begin to disappear or get lost? Perhaps. A possible solution would be to assign a fingertip pulse oximeter to each physician or nurse who has a need for one, and to expect them not to lose their own personal device. Could continuous fingertip pulse oximetry prevent hypoxic events during in-hospital transports? Yes. A prospective study testing this practice would be easy to do. The connection of fingertip monitors to a hospital’s electronic medical record (EMR) would not be practical, but the purpose of the monitor is to keep patients safe. Whether the monitor readings are recorded in a vital sign readout of the EMR is a less important factor. 

In conclusion, the post-surgical transport of a patient from the operating room to the PACU is a period of patient risk. The routine use of supplemental oxygen and the routine use of pulse oximetry can help anesthesiologists decrease this risk of inadequate breathing and low oxygen saturation during transport. 

CODA: The transport of post-operative patients from the OR to the ICU is a more complex undertaking than transport of patients from the OR to the PACU. The distances between the OR and the ICU are greater than the distance between the OR and the PACU. The ICU may be on a different floor and necessitate an elevator ride. A patient bound for the ICU may be asleep and intubated, which requires the anesthesiologist to ventilate the lungs with an Ambu bag attached to the endotracheal tube during the transfer. The patient may be requiring infusions of vasoactive drugs to maintain blood pressure within safe limits. The anesthesiologist may be supervising the transfusion of blood, platelets, or plasma. Managing all these factors while vigilantly watching the monitor screen while riding in an elevator with a sick patient is a challenging experience. Indeed, the post-surgical transport of a patient from the OR to the ICU requires an anesthesiologist to manage a rolling intensive care unit experience.



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